A demand for rapid processing of silver halide photographic material is increasing in these days. In general, silver bromide is used in photographic materials. However, for rapid processing of photographic materials, it is desirable that silver chloride is used in them. However, silver chloride grains have problems in that they weakly adsorb dyes, that they are weakly sensitized with spectral sensitizing dyes and that the storability of the grains themselves is poor. Accordingly, the use of tabular grains having large surface area and having large adsorptive capacity of dye in silver halide photographic materials is advantageous. As tabular grain, tabular grains having {111} faces as the major planes are generally used in view of the easiness of the production, the photographic sensitivity and the sharpness of the materials. However, the tabular grains having {111} faces as the major planes have a problem in that their intrinsic desensitization due to dyes is great.
According to A. Mignot, E. Francois & M. Catinat, "Cristaux de Rbomure D'argent Plats, Limites par des Faces (100) et non Macles", Journal of Crystal Growth 123 (1974), 207-213, it is reported that they have observed tabular silver bromide crystals with {100} faces having square or rectangular major planes.
According to the disclosure of U.S. Pat. No. 4,063,951, the tabular grains with {100} crystalline faces are formed from monodisperse seed grains and they are ripened in the presence of ammonia to have a mean aspect ratio falling within the range between 1.5 and 7. U.S. Pat. No. 4,386,156 mentions a method for producing emulsions of tabular silver bromide grains, in which seed grains are ripened in the absence of a non-halide complexing agent for silver ions, to form tabular silver bromide grains having a mean aspect ratio of 8 or more. A method for producing tabular grains having a high silver chloride content is illustrated in EP-A-534395.
The inventors of the present invention tried to use the tabular grains having {100} faces as the major planes as silver halide grains to confirm that such tabular grains cannot meet practical use because they particularly weakly adsorb dyes.
Accordingly, the inventors have conducted extensive investigations in order to obtain dyes excellent in adsorption on tabular silver halide grains having {100} faces as the major planes, and have achieved the present invention.